| cylsph_c |
|
Table of contents
Procedure
cylsph_c ( Cylindrical to spherical )
void cylsph_c ( SpiceDouble r,
SpiceDouble clon,
SpiceDouble z,
SpiceDouble * radius,
SpiceDouble * colat,
SpiceDouble * slon )
AbstractConvert from cylindrical to spherical coordinates. Required_ReadingNone. KeywordsCONVERSION COORDINATES Brief_I/OVARIABLE I/O DESCRIPTION -------- --- ------------------------------------------------- r I Distance of point from z axis. clon I Angle (radians) of point from XZ plane. z I Height of point above XY plane. radius O Distance of point from origin. colat O Polar angle (co-latitude in radians) of point. slon O Azimuthal angle (longitude) of point (radians). Detailed_Input
r is the distance of the point of interest from z axis.
clon is the cylindrical angle (radians) of the point from the
XZ plane.
z is the height of the point above XY plane.
Detailed_Output
radius is the distance of the point from origin.
colat is the polar angle (co-latitude in radians) of the point.
The range of `colat' is [-pi, pi].
slon is the azimuthal angle (longitude) of the point
(radians). `slon' is set equal to `clon'.
ParametersNone. ExceptionsError free. FilesNone. ParticularsThis returns the spherical coordinates of a point whose position is input through cylindrical coordinates. Examples
The numerical results shown for these examples may differ across
platforms. The results depend on the SPICE kernels used as
input, the compiler and supporting libraries, and the machine
specific arithmetic implementation.
1) Compute the cylindrical coordinates of the position of the
Moon as seen from the Earth, and convert them to spherical
and rectangular coordinates.
Use the meta-kernel shown below to load the required SPICE
kernels.
KPL/MK
File name: cylsph_ex1.tm
This meta-kernel is intended to support operation of SPICE
example programs. The kernels shown here should not be
assumed to contain adequate or correct versions of data
required by SPICE-based user applications.
In order for an application to use this meta-kernel, the
kernels referenced here must be present in the user's
current working directory.
The names and contents of the kernels referenced
by this meta-kernel are as follows:
File name Contents
--------- --------
de421.bsp Planetary ephemeris
naif0012.tls Leapseconds
\begindata
KERNELS_TO_LOAD = ( 'de421.bsp',
'naif0012.tls' )
\begintext
End of meta-kernel
Example code begins here.
/.
Program cylsph_ex1
./
#include <stdio.h>
#include "SpiceUsr.h"
int main( )
{
/.
Local variables
./
SpiceDouble clon;
SpiceDouble colat;
SpiceDouble et;
SpiceDouble lt;
SpiceDouble pos [3];
SpiceDouble r;
SpiceDouble radius;
SpiceDouble rectan [3];
SpiceDouble slon;
SpiceDouble z;
/.
Load SPK and LSK kernels, use a meta kernel for
convenience.
./
furnsh_c ( "cylsph_ex1.tm" );
/.
Look up the geometric state of the Moon as seen from
the Earth at 2017 Mar 20, relative to the J2000
reference frame.
./
str2et_c ( "2017 Mar 20", &et );
spkpos_c ( "Moon", et, "J2000", "NONE", "Earth", pos, < );
/.
Convert the position vector `pos' to cylindrical
coordinates.
./
reccyl_c ( pos, &r, &clon, &z );
/.
Convert the cylindrical coordinates to spherical.
./
cylsph_c ( r, clon, z, &radius, &colat, &slon );
/.
Convert the spherical coordinates to rectangular.
./
sphrec_c ( radius, colat, slon, rectan );
printf( " \n" );
printf( "Original rectangular coordinates:\n" );
printf( " \n" );
printf( " X (km): %19.8f\n", pos[0] );
printf( " Y (km): %19.8f\n", pos[1] );
printf( " Z (km): %19.8f\n", pos[2] );
printf( " \n" );
printf( "Cylindrical coordinates:\n" );
printf( " \n" );
printf( " Radius (km): %19.8f\n", r );
printf( " Longitude (deg): %19.8f\n", clon*dpr_c ( ) );
printf( " Z (km): %19.8f\n", z );
printf( " \n" );
printf( "Spherical coordinates:\n" );
printf( " \n" );
printf( " Radius (km): %19.8f\n", radius );
printf( " Colatitude (deg): %19.8f\n", colat*dpr_c ( ) );
printf( " Longitude (deg): %19.8f\n", slon*dpr_c ( ) );
printf( " \n" );
printf( "Rectangular coordinates from sphrec_c:\n" );
printf( " \n" );
printf( " X (km): %19.8f\n", rectan[0] );
printf( " Y (km): %19.8f\n", rectan[1] );
printf( " Z (km): %19.8f\n", rectan[2] );
printf( " \n" );
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, the output was:
Original rectangular coordinates:
X (km): -55658.44323296
Y (km): -379226.32931475
Z (km): -126505.93063865
Cylindrical coordinates:
Radius (km): 383289.01777726
Longitude (deg): 261.65040211
Z (km): -126505.93063865
Spherical coordinates:
Radius (km): 403626.33912495
Colatitude (deg): 108.26566077
Longitude (deg): 261.65040211
Rectangular coordinates from sphrec_c:
X (km): -55658.44323296
Y (km): -379226.32931475
Z (km): -126505.93063865
2) Create a table showing a variety of cylindrical coordinates
and the corresponding spherical coordinates.
Corresponding spherical and cylindrical coordinates are
listed to three decimal places. All input and output angles
are in degrees.
Example code begins here.
/.
Program cylsph_ex2
./
#include <stdio.h>
#include "SpiceUsr.h"
int main( )
{
/.
Local parameters.
./
#define NREC 11
/.
Local variables.
./
SpiceDouble colat;
SpiceDouble radius;
SpiceDouble rclon;
SpiceDouble slon;
SpiceInt i;
/.
Define the input cylindrical coordinates. Angles
in degrees.
./
SpiceDouble r [NREC] = { 0.0, 1.0, 1.0,
0.0, 1.0, 1.0,
0.0, 1.0, 1.0,
0.0, 0.0 };
SpiceDouble clon [NREC] = { 0.0, 0.0, 90.0,
0.0, 180.0, -90.0,
0.0, 45.0, 180.0,
180.0, 33.0 };
SpiceDouble z [NREC] = { 0.0, 0.0, 0.0,
1.0, 1.0, 0.0,
-1.0, 0.0, -1.0,
1.0, 0.0 };
/.
Print the banner.
./
printf( " r clon z radius colat slon \n" );
printf( " ------- ------- ------- ------- ------- -------\n" );
/.
Do the conversion. Output angles in degrees.
./
for ( i = 0; i < NREC; i++ )
{
rclon = clon[i] * rpd_c ( );
cylsph_c ( r[i], rclon, z[i], &radius, &colat, &slon );
printf( "%8.3f %8.3f %8.3f ", r[i], clon[i], z[i] );
printf( "%8.3f %8.3f %8.3f\n",
radius, colat * dpr_c ( ), slon * dpr_c ( ) );
}
return ( 0 );
}
When this program was executed on a Mac/Intel/cc/64-bit
platform, the output was:
r clon z radius colat slon
------- ------- ------- ------- ------- -------
0.000 0.000 0.000 0.000 0.000 0.000
1.000 0.000 0.000 1.000 90.000 0.000
1.000 90.000 0.000 1.000 90.000 90.000
0.000 0.000 1.000 1.000 0.000 0.000
1.000 180.000 1.000 1.414 45.000 180.000
1.000 -90.000 0.000 1.000 90.000 -90.000
0.000 0.000 -1.000 1.000 180.000 0.000
1.000 45.000 0.000 1.000 90.000 45.000
1.000 180.000 -1.000 1.414 135.000 180.000
0.000 180.000 1.000 1.000 0.000 180.000
0.000 33.000 0.000 0.000 0.000 33.000
RestrictionsNone. Literature_ReferencesNone. Author_and_InstitutionJ. Diaz del Rio (ODC Space) B.V. Semenov (JPL) W.L. Taber (JPL) E.D. Wright (JPL) Version
-CSPICE Version 1.1.0, 02-JUL-2021 (JDR)
Changed the argument names "lonc" and "lon" to "clon" and
"slon" for consistency with other routines.
Edited the header to comply with NAIF standard.
Added complete code examples.
-CSPICE Version 1.0.2, 26-JUL-2016 (BVS)
Minor headers edits.
-CSPICE Version 1.0.1, 08-FEB-1998 (EDW)
Corrected and clarified header entries.
-CSPICE Version 1.0.0, 25-OCT-1997 (EDW) (WLT)
Index_Entriescylindrical to spherical |
Fri Dec 31 18:41:03 2021